British Gas owner Centrica has announced it is on track to deliver profits of £1.4 billion this year.

The announcement comes just a day before British Gas increases household energy bills by an average of six per cent.

Analysts are predicting Centrica, one the UK's 'big six' utility companies, will deliver a six per cent rise in pre-tax profits from its British Gas residential arm this year to £575 million.

British Gas announced last month it would raise its household energy tariffs by an average of six per cent, effective from this coming Friday.

E.ON, the only utility provider of the big six operating in the UK yet to announce price hikes is reported to be planing to increase its prices by an average of 11 per cent for early next year.

Centrica, which has 15.8 million customers, has blamed rising energy bills on the costs of carbon reduction targets and upgrading the UK's gas and electricity grids – adding around £50 to the average utility bill.

The group said its wholesale gas prices for the winter had also risen by 13 per cent on a year ago.

Centrica also noted today it had lost seven per cent of its customers in the past year, including 43,000 business customers.

And its UK residential services business, which installs and maintains boilers, is on track to deliver double-digit growth this year, despite boiler installations being down 16 per cent on a year ago.

SSE was the first of the so-called 'big six' energy suppliers to announce further price rises for both gas and electricity back in August, adding a rise of nine per cent to both its gas and electricity prices effective from October 15, 2012.

Centrica said residential gas consumption for the first 10 months of the year was nine per cent higher than a year earlier as a result of colder than normal weather.

The group, which makes most of its profit from upstream gas and oil exploration, provides gas and electricity to almost 16 million households.

Last February Centrica acquired a number of North Sea oil and gas assets from Total E&P UK Ltd in a $388 million (£246 million) deal.

The utility firm agreed a £2billion supply deal in February 2011 with Quatargas for 2.4 million tonnes of liquefied natural gas.

Centrica went on to announced a a £13 billion supply deal with Norwegian state-owned oil and gas producer Statoil in November 2011 – beginning 2015 – which it said would guarantee gas supply for UK homes for the next 10-years, based on a figure of 3.5 million homes.

Production at Centrica's UK upstream business is expected to rise by 15 per cent next year.

The UK Government has ordered an urgent inquiry this week following claims made by a whistleblower the UK's £300 billion wholesale gas market had been “regularly” manipulated by big power companies.

The whistleblower, who worked for ICIS Heren, a company responsible for setting benchmark wholesale gas prices, highlighted unusual trading in the British wholesale gas market on September 28 of this year.

This is a key date in the wholesale trading calender as it marks the end of the financial year for gas trading and therefore has implications on future pricing.

The trader provided data which shows the price gas contracts were being bought and sold for on September 28 – called day ahead gas contracts – dropped sharply at 4:30pm, the same time ICIS Heren took its snapshot for its benchmark reading of the market.

ICIS Heren has warned the energy regulator Ofgem it had seen evidence of suspect trading on 28 September.

City watchdog the Financial Services Authority is investigating the claims.

A recent European gas hub report published by ICIS also points to a “strong industry resistance” from energy firms to tighten regulation of how wholesale prices are set for gas and electricity.

The report states: "The recent London interbank offered rate (Libor) scandal engulfing major financial institutions also prompted a European commission consultation in early September on the regulation of key indices, including those for coal, natural gas and electricity.

“However, strong industry resistance to many of the proposals has so far resulted in the watering down of many elements of the current regulatory proposals.”